U.S. Pat. No. 5,193,743, corresponding to German Unexamined Patent Application No. DE 41 21 372, describes a device for injecting a fuel-gas mixture having a fuel-injection valve and a cup-shaped gas-containing (gas-enveloping) sleeve which axially surrounds, at least in part, the valve end of the fuel injection valve with its casing part and radially surrounds the valve end of the fuel injection valve, at least in part, with its base part. The design of the gas-containing sleeve is such that its base part has a concentric passage opening shaped diagonally to the valve end of the fuel-injection valve. In this manner, an annular gas gap is formed between an apertured spray disk situated at the downstream end of the fuel-injection valve and the base part of the gas-containing sleeve. This annular gas gap directly surrounds the passage opening.
Gas is supplied via ports in the casing part of the gas-containing sleeve, as well as via gas-flow-control channels. The axial dimensions of the annular gas gap are adjusted by axially sliding the gas-containing sleeve up to a stop face of the valve support. The actual value of the gas flow rate is subsequently measured, and the adjustment to the setpoint value is then made by removing material either from the stop face or from the base part of the gas-containing sleeve, or rather the base part is plastically deformed.